The efforts of Emily Thornberry MP and her team in Islington South & Finsbury paid off. Photograph: David Levene

The Nick Clegg surge may have all but died across the country as a whole, but in the capital the Cameron surge faltered too. As I write, some of London's results are still to be declared, yet it is already clear that the Conservatives met with more resistance and secured far fewer gains than they'd expected.

The Lib Dems have taken only one target seats from either of their larger rivals, but with the surprise exception of Richmond Park they have repelled the Conservative advance in the suburban south-west. And Labour can regard its successful defence of finely balanced marginals as gutsy and significant triumphs.

I headed to the count for Tooting late last night glumly anticipating defeat for Sadiq Khan, followed by similar fates for his colleagues Karen Buck in Westminster North, Clive Efford in Eltham, Andy Slaughter in Hammersmith and even Jon Cruddas in Dagenham and Rainham. One by one they emerged victorious despite the message of the polls and the lavishly resourced campaigns of their Tory opponents.

How did they survive? Tactical voting, Gordon Brown's core vote approach, even disillusion with Tory London mayor Boris Johnson could all be part of it, but I'm inclined to look to local factors first. The MPs concerned are all grassroots grafters who know their territory and those they represent. Cruddas has battled the BNP street by street. Slaughter is Hammersmith born and raised. Reports on Buck's campaign repeatedly included constituents declaring their love for her.

Their opponents could make few similar claims. Khan lambasted his, the very right-wing Mark Clarke, for indulging in "dirty politics". Joanne Cash, beaten by Buck, complained bitterly about her treatment by the media, and not without some cause, but her reputation as a Cameron "chosen one" went before her. The paradox of Shaun Bailey, the most visible figurehead for Dave's new Tory order, is that his over-promotion as a man of the street made him seem manufactured rather than authentic. An important lesson of these Tory candidates' defeats is that voters know a good, grounded, straightforward MP when they're lucky enough to have one and on polling day, they do not forget.

Admirers of Emily Thornberry, who seemed doomed to defeat by Lib Dem Bridget Fox in Islington South and Finsbury but held on, say that she bears out the same point. Perhaps Tony McNulty's defeat in Harrow East does too, in exactly the opposite way. Margaret Hodge's hammering of Nick Griffin in Barking is another vindication of hard slog activism on the ground. When Labour gets round to analysing where election 2010 went wrong, they would be wise to learn from what went right last night.